The high strength and low weight characteristics of fiber reinforced articles have in recent years accounted, at least in part, for the popularity of such articles over metallic articles manufactured by such prior art processes as the machining, casting or forging of a plurality of metallic component parts and the subsequent assembly of such parts. The wide range of shapes and the resulting minimization of required component parts associated with fiber reinforced articles has also contributed to such popularity. An example of a modern method for manufacturing reinforced fiber aircraft propeller blades is disclosed in U.S. patent application Ser. No. 193,519 filed Oct. 2, 1980, in the name of Harry A Nutter, Jr., and entitled "Method of Making Fiber Reinforced Articles".
In the Ser. No. 193,519 patent application, an aircraft propeller blade is manufactured by first, forming a spar-foam subassembly by providing a structural spar of a material such as aluminum, coating the spar with a thermosetting adhesive and molding a thermosetting adhesive coated foam about the leading and trailing surfaces of the spar. A fiber reinforced skin or covering is then formed about the exterior of the spar-foam subassembly. As set forth in greater detail in the Ser. No. 193,519 application, the covering comprises a number of layers of woven fiberglass cloth, each layer retained in position over the spar-foam subassembly by stitching. Thereafter, a liquid plastic such as a synthetic polymerizable material is vacuum injection molded into the cloth and then cured. Those skilled in the art of manufacturing reinforced fiber articles will readily appreciate that stitching a plurality of cloth layers about a form such as the spar-foam subassembly requires substantial time and therefore contributes significantly to the manufacturing costs of such an article. In particular, where the article is of significant dimension and substantially complex shape, the stitching is often required to be performed by hand in a relatively time consuming fashion.
Accordingly, it is a principal object of the present invention to provide an improved method of manufacturing fiber reinforced articles.
It is another object to provide such a method characterized by enhanced economy and ease of performance.
It is another object to provide such a method wherein the time required for securing fibrous material to a form or subassembly prior to injection molding with a thermosetting substance, is minimized.
It is another object to provide such a method wherein such securing of the fibrous material to the form does not adversely affect the strength of the fibrous material or the finished article.